Never in a
million years …
Maybe that’s what some people
thought 30 years ago about low-E
glass—a glass that could actually
absorb the sun’s heat and re-direct
it to its source. And look where we
are now. Low-E glass is a mainstream
product found on just about
all windows produced today.

Just as low-E glass may have
seemed like a far-off concept so
many years ago, there are early development
technologies today
that could also be used to create
energy-efficient windows, but have
yet to reach their full commercial
potential. High costs, production
and even installation challenges
have hindered such products from
reaching mass market acceptance.

In order to increase the market
acceptance of these products, the
Department of Energy (DOE) and its
Office of Energy Efficiency and
Renewable Energy’s (EERE) Building
Technologies Program (BTP) solicited
proposals as part of a research funding
project (applications were due July 8). The DOE has made funds
available that will be put toward the
development/selection of innovative
new technologies, accompanying
production design and engineering
and commercialization that will
advance market adoption of highly
insulating windows for residential
buildings in cold climates. According
to the DOE’s funding solicitation, a
key requirement of this opportunity
is the ability of the product to
achieve energy-performance targets
(R5 or better) at a market-acceptable
cost premium (less than $4/square
foot). By doing so, the hope is to
increase adoption and national
energy savings. The DOE estimates
that approximately $2 million will be
available for up to three awards and
projects will be 50-50 cost shared
between industry and the federal
government. DOE also expects to
notify applicants accepted to receive
the awards by November 2008.

Zero-Energy Buildings
But creating these new technologies
requires the support of
the fenestration industry. This past
June Marc LaFrance, BTP technology
development manager, gave a
presentation during the American
Architectural Manufacturers
Association summer meeting in
Hershey, Pa., where he discussed
this funding opportunity.

“The goal of the BTP is to create
technologies and design
approaches that enable the construction of net-zero energy buildings
at low incremental cost by
2025,” LaFrance said during the
presentation. “In order to get
there, we need R5 windows.”
LaFrance explained that the technologies
most commonly used
today for energy-efficient windows
are low-E glass and insulating
glass units (IGU). While the
products do very well, the market
is stuck in terms of reaching an R5
value. “That’s really going to take
something like a triple-glazed unit
to get there,” said LaFrance.

According to information from
the DOE, most of today’s highly
insulating products are expensive,
sometimes heavy and not widely
available; they also have less readily
apparent consumer benefits
and manufacturers have been
reluctant to invest in expensive
production lines without clear
market pull.

“In order for them to become
more available it requires engineering
and manufacturing
investments to bring the costs down,” said LaFrance.

Through this research-funding
project, the industry and consumers
may find these products
viable—especially if energy costs
continue to increase. The DOE
estimates that windows typically
contribute about 30 percent of
overall building heating and cooling
loads with an annual impact of
about 4.0 quads (quadrillion Btu),
with an additional potential savings
of 1 quad from daylight use.
In order to meet the goal of creating
zero-energy buildings an
“aggressive program” is needed to
change the energy-related role of
windows in buildings.

“We need cost-effective products
to get to these zero-energy
buildings,” said LaFrance. “To get
there, there has to be an investment
in technology.”

Triple-glazed units may be a
main focus area of this particular
research funding project, but there
are other products and technologies
being developed that could
also be used in the construction of
a window with an R5—or even
greater—rating. While advanced
technologies are not the focus of
this project, they could be considered
so long as they provide the
near commercialization required
by this funding project. Looking
even further toward the future and
considering increasingly high
energy costs, technologies such as
vacuum insulating glass (VIG) and
dynamic glazing, are just starting
to emerge and could very well
make their way into the conventional
usage.

Vacuum Insulating Glass
While the development of vacuum
insulating glazing (VIG) is just
starting to emerge in North America,
the technology has been commercially
available in Japan since the
mid-1990s, according to the Efficient
Windows Collaborative’s (EWC)
June 2008 newsletter. VIGs consist
of two glass lites with an evacuated
spacing gap that contains
numerous small support pillars.
The EWC newsletter explains that
VIGs are designed so that there is
no conductive or convective heat
transfer between the glass lites.
Guardian Industries in Auburn
Hills, Mich., is one company that
has a VIG in development phases.

“With VIGs you eliminate everything
between the lites of glass
and that creates a vacuum, which
generates the highest possible
insulating value,” says Andy
Russo, market development manager
for Guardian. “The bare
essentials are the glass and the
vacuum; because there is a vacuum
you typically need something
to keep the glass from collapsing
on itself, so a spacer and some
way to hold the glass together at
the edges.”

According to Russo the technology
behind VIGs is not new; in
fact the technology is the same as
that used in products such as
thermoses.

“The concept is the same—it
keeps hot things hot and cold
things cold,” says Russo. “It’s the
same idea, you’re just applying it
to a window.”

Hurdles to Cross
While the VIG technology could
be used to create a highly insulating
window, it’s in early development
stages and faces a number
of hurdles before it will be
grasped fully.

“The industry is pretty conservative and doesn’t accept change
very readily,” says Russo. “Because
the technology itself is generally
more expensive than a traditional
glass assembly, something like the
[increasing] price of energy is
what will draw interest.”

He continues, “I think interest
has been building over the years,
especially if you look at what’s
going on in Europe and the amount
of triple glazing that’s used there.
Here, we’re starting to see more
triple glazed units, especially in
aftermarket applications.”

The technology will have to
overcome other obstacles as well,
including high costs. In fact, one
source says producing a VIG
would double the cost of a standard
IGU. But according to Russo,
exactly how the technology will
affect the cost of a window is
uncertain.

“The cost of the material might
go up a little bit, but [as far as] the
actual sales price of the window,
that’s kind of up to the people who
are first bringing it to market,”
Russo says. “If you’re the first on
the market you could charge
whatever you want. It doesn’t necessarily
mean that the market will
buy it across the board. If the window
manufacturer has an exclusive
he might charge more; if the
company has three or four competitors
it might charge less.”

Cost is not the only challenge.
There are also technical issues
that have prevented the product
from coming to market. These
include the ability of the glass to
maintain a vacuum over time and
the structural and thermal performance
of the window in total.
Russo explains, “You can create
the IG assembly to perform a certain
way, but when you put it into
the frame or structure in the wall
it might act a different way.”

Overall aesthetics may also be a
disadvantage for some, because a
VIG has a different appearance than
a typical IGU; VIGs are very thin.

“The look is going to be different
and the spacer may or may not be
visible. If it’s visible that might be a
negative for some,” says Russo.

Gaining Acceptance
But high cost is probably the
biggest consideration. So, what
will it take to bring the cost down
to a more acceptable price point?

“The first thing is to make a
product that uses components
that are not prohibitive,” says
Russo. He explains that if a product
required a very exotic material,
for example, the cost would
likely be extremely high. “The idea
behind the VIG is a good one
because you start with materials
that are readily available and generally
proven and inexpensive. It’s
basically glass, the material to
bond the glass and a spacer. If you
put those things into an assembly,
the assembly cost itself will be relatively
inexpensive. What you
have to do is figure out a way to
make it and make it relatively
inexpensively.”

If energy costs continue to
increase, products such as VIG
windows can help consumers offset
their energy bills—but first
there has to be widespread
acceptance.

“The premium [consumers pay
for the windows] could be outweighed
by the savings. I don’t
know what the payback would be
… but if you double or triple the
performance of a window,
depending on where you live, that
generates a tremendous amount
of savings on an annual basis,”
says Russo. Because people are
sometimes skeptical about new
technologies, the challenge will be
getting the word out to consumers
in a way that they are willing to
adapt. Russo says having the
whole market behind the new
technology would help make it
easily adaptable.

Dynamic Glazing
Dynamic glazing (variable
transmittance/electronically
tintable glass) is another technology
on the verge of reaching full
market commercialization. On its
own this type of glass does not
have an R5 value, but when combined
with other technologies,
such as a triple-glazed unit, it can
meet that value. Sage
Electrochromics Inc. based in
Faribault, Minn., is one company
currently producing this type of
glass for use in standard IGUs.
John Van Dine, president of the
company, says the way his company
produces its dynamic glass is
similar to the way low-E is
deposited on the glass.

“Of course, there are different
material types, but it’s done in a
manner that very much mirrors
the way low-E is produced,” said
Van Dine. “[Our technology] is
applied to the second surface of
the IGU and then when you supply
low-voltage power to it you
can take the glass from a hightransmission
condition to a very
low transmission—all the way
down to 3-percent visible light
transmittance—and move the
solar heat gain coefficient (SHGC)
down to .09,” says Van Dine. “You
still maintain the view and have
connection to the outdoors but
the glass has stopped all of the
direct solar heat gain and the glare
without the use of shades or
blinds. Then when the environment
outside changes (when it’s
cloudy, for example) you can untint
the glass and harvest a great
deal of natural daylight.”

According to Van Dine, his company
first delivered products commercially
in 2004 in a very limited
way.

“We did that exclusively with
Velux in a limited manner. In 2006
we brought online a larger manufacturing
capability here in
Faribault, and have been delivering
products since then,” he says,
adding that the company also has
plans to expand those capabilities.

Market Focus
He says the company is currently
focusing efforts toward the commercial architectural market,
but does have plans to expand
more into residential.

“The only reason we have not
been more proactive in the residential
market is because as a
growing company with a new
product there is only so much we
can do,” says Van Dine. “We felt as
though we wanted to get our
delivery logistics into a different
place before we approach that
market more proactively. We do
residential work from time to
time; we’re just not proactively targeting that audience as of
today.”

He adds, “The value of our
product is its ability to help the
design community gain points
within the LEED accreditation
system. The product falls into four
categories and with the changes
happening to the LEED program
… we believe we may be able to
garner more points for the design
community in the future.”

Challenges and Considerations
And just as the VIG technology
is facing development challenges,
so too have these products.

“Because we are a low-volume
format, at this time we have a fairly
high price point and production
limitations,” says Van Dine.
“We need to get the product out
into a larger format; our current
operations limit us to a maximum
size and the design community
would like to see larger sizes.
Those are the main obstacles to
broaden our use.”

Though the company has not yet
fully ventured into the residential
market, the product does offer at
least one feature that may be particularly
attractive to some window
manufacturers. Considering the
DOE’s proposed revisions to its
ENERGY STAR® program, some window
manufacturers may like the
fact that the technology allows consumers
to control the SHGC of their
windows. Van Dine says employees
from his company have attended
some meetings involving these
changes and “it is very clear that
the real answer to the conundrum
is[that] we need a glazing that can
respond to different conditions,” he
says. “If you just pause and ask
yourself ‘why do we put windows in a building … in a home …?’ there’s
only one reason,
and that’s because people occupy buildings. If people
did not occupy buildings there are other materials
that have an R-value of 30 and these materials
don’t need maintenance like windows do. We use
windows because people want the natural light and
they want the connection to the outdoors,” Van
Dine says. “Unfortunately, when the sun comes
around we have to pull shades and blinds to block
it and that negates the reason we used the glass in
the first place. Electronically tintable glass allows
consumers to use the window to stop the energy
when they need to, but still maintain the view and
connection to the outdoors. It’s a product that
deals with the urgencies of reducing energy consumption
and it responds to the desires of those
who occupy the buildings.”

Into the Mainstream
Technology, namely innovation in building
design, plays a major role in improving the current energy situation.
And because people generally
want more light in their houses, new window
technologies are poised to be a significant contributor
in energy efficiency moving forward.

“New technologies that increase the insulating
values of the windows will allow [consumers] to have
houses with more windows and more light without
impacting their comfort level and energy bill,” says
Russo. “The industry has to move forward with these
products in order to make our lives better.”

Van Dine agrees.

“If you look at the energy consumption of a
building the weakest link is the envelope
(doors/windows),” he says. “Dynamic technologies
can respond to the current situation of the
sun, whether it’s sunny or cloudy and adjust the
SHGC of the window.”

He continues, “The environment in which we
live is constantly changing—day by day, seasonally,
it changes for different orientations of a building
and it’s different for different geographies. The
glazing industry today is based upon glass that is
static. We now need a glazing that can respond to
the parameters and the changes that take place
throughout the day and geographies. So I don’t
think we really have a choice but to move in that
direction if we really hope to make an impact on
reducing the energy consumption of buildings.”